Process for production of macrostructures of a microporous material

ABSTRACT

The invention involves a process for production of macrostructures of a microporous material. The process is characterized by the fact that seeds formed in or introduced by ion exchange or adsorption to a porous organic ion exchanger with the desired size, shape and porosity are made to grow and form a continuous structure by further deposition of inorganic material from a synthesis solution under hydrothermal conditions. The organic ion exchanger can be eliminated by chemical destruction or dissolution and, in so doing, leaves behind an inorganic microporous structure with the size and shape of the employed organic ion exchanger.

This application is a continuation of U.S. application Ser. No.10/379,876, filed Mar. 5, 2003 now U.S. Pat. No. 6,949,239, now allowed;which is a divisional of U.S. application Ser. No. 09/312,877 filed May17, 1999, now U.S. Pat. No. 6,569,400 which claims priority to SwedishPatent Application No. 9802303-9, filed Jun. 30, 1998.

This application claims priority to Swedish Patent Application No.9802303-9, filed Jun. 30, 1998.

FIELD OF THE INVENTION

The present invention concerns a process for production ofmacrostructures with controlled size and shape of a microporousinorganic material.

BACKGROUND OF THE INVENTION

Microporous material is characterized by a large specific surface areain pores with a pore radius below 20 Å and is used in a large number ofapplications of considerable commercial importance. In most of theseapplications, the fact that the phase interface between the solid porousmaterial and the medium (liquid or gas) in which it is used is large isof decisive importance. Heterogeneous phase catalysts for refineryprocesses for petrochemical conversion processes and for differentenvironmentally related applications are often based on microporousmaterial. Adsorbents for selective adsorption in the gas or liquid phaseare microporous materials, like most of the inorganic ion exchangersused for selective separation of ionic compounds. In addition to theselarge scale and relatively established applications, microporousmaterials have recently become increasingly interesting in a number ofmore technologically advanced areas. Examples include use in chemicalsensors, in fuel cells and batteries, in membranes for separation orcatalytic purposes, during chromatography for preparative or analyticalpurposes, in electronics and optics and in the production of differenttypes of composites.

Although a large phase interface is often a fundamental requirement foruse of porous materials in different applications, a number ofadditional requirements related to the specific area of application areimposed on these materials. The large phase interface available in themicropores must be accessible and useable. Porosity, pore size and poresize distribution in large pores (meso- and macropores) are thereforeoften of major significance, especially when mass transport can be arate-limiting factor. The chemical properties on the surface of theporous material can also be of decisive importance for the performanceof the material in a given application. In this context, the purity ofthe material is, consequently, also significant. In most practicalapplications, the size and shape of the porous macrostructures and thedegree of variation of these properties are of decisive importance.During use, the size and shape can influence properties like masstransport within the porous structures, pressure drop over a bed ofparticles of the material and the mechanical and thermal strength of thematerial. Which factor or factors are most important will vary stronglybetween different applications and are also highly dependent on thelayout of the process in which the application occurs. Techniques thatpermit production of a material with increased specific surface area,pore structure (pore size/pore size distribution), chemical composition,mechanical and thermal strength, as well as increased and uniform sizeand shape, are consequently required to tailor porous inorganicmacrostructures to different applications.

Microporous materials can be divided into crystalline molecular sievesand amorphous materials. Molecular sieves are characterized by the factthat they have a pore system through their regular crystal structure, inwhich the pores have a very well defined size in the range 2-20 Å withan exact value determined by the structure. The size of most moleculesthat are gases and liquids at room temperature, both inorganic andorganic, is found within this size range. By selecting a molecular sievewith the appropriate pore size, use of molecular sieves for separationof one substance (one type of molecule) in a mixture is made possible byselective adsorption, hence the name molecular sieve. In addition toselective adsorption of uncharged substances, the well-defined microporesystem of the molecular sieve offers a possibility for selective ionexchange of charged species and size-selective catalysis. In this caseproperties other than the micropore structure in molecular sieves arealso of major significance, like ion exchange capacity or specificsurface area and acidity. Molecular sieves can be divided into a numberof subgroups, depending on chemical composition and structure. Acommercially important subgroup are the zeolites, which, by definition,are crystalline microporous aluminosilicates. Another interestingsubgroup is the microporous metal silicates, which are structuralanalogs of the zeolites, but do not contain any (or very little)aluminum.

A summary of the prior art, in terms of production, modification andcharacterization of molecular sieves, is described in the book MolecularSieves—Principles of Synthesis and Identification (R. Szostak, BlackieAcademic & Professional, London, 1998, Second Edition). In addition tomolecular sieves, amorphous microporous materials, chiefly silica,aluminum silicate and aluminum oxide, have been used as adsorbents andcatalyst supports. A number of long-known techniques, like spray drying,prilling, pelletizing and extrusion, have been and are being used toproduce macrostructures in the form of, for example, sphericalparticles, extrudates, pellets and tablets of both micropores and othertypes of porous materials for use in catalysis, adsorption and ionexchange. A summary of these techniques is described in CatalystManufacture, A. B. Stiles and T. A. Koch, Marcel Dekker, New York, 1995.

Because of limited possibilities with the known technique, considerableinvestment has been made to find new ways to produce macrostructures ofmicroporous materials, with a certain emphasis on those in the form offilms.

EP 94/01301 describes-production of films of molecular sieves by aprocess in which seed crystals of molecular sieves are deposited on asubstrate surface and then made to grow together into a continuous film.GB 94/00878 describes production of films of molecular sieves byintroduction of a substrate to a synthesis solution adjusted for zeolitecrystallization and crystallization with a gradual increase in synthesistemperature. SE 93/00715 describes production of colloidal suspensionsof identical microparticles of molecular sieves with an average sizebelow 200 nm. SE 90/00088 describes a method for production of anadsorbent material in the form of a monolith by impregnation of themonolithic cell structure with a hydrophobic molecular sieve, followedby partial sintering of the molecular sieve with the material from whichthe cell structure is constructed.

Although a number of different techniques already exist for productionof microporous inorganic macrostructures with the desired size andshape, these techniques are beset with a number of limitations thataffect the properties of the macrostructures during use in the intendedapplication. Most of these techniques require the use of a binder togive the structure acceptable mechanical strength. This binder oftenadversely affects other desired properties, like high specific surfacearea and uniform chemical composition. For most of the existingtechniques, other possibilities for keeping variations in size and shapewithin narrow limits are sharply constrained. If a well defined size isdesired with a narrow particle size distribution, one is most oftenobliged to carry out processing by separation, which leads toconsiderable waste during manufacture. The use of different types ofbinders also affects the pore structure in the resulting macrostructureand it is often necessary to find a compromise, in which the desiredpore structure is weighed against the mechanical properties of thematerial. It is often desirable to have a bimodal pore size distributionin the macrostructures of macroporous materials, in which the microporesmaintain a large specific phase interface, whereas the larger pores inthe meso- or macropore range permit transport of molecules to thesurface and, in this way, prevent limitations caused by slow diffusion.During production of microporous macrostructures according to the knowntechnique, a secondary system of pores within the meso- and/or macroporerange can be produced by admixing a particulate inorganic material or byadmixing organic material (for example, cellulose fibers), which arelater eliminated by calcining. Both of these techniques, however,produce an adverse effect on the other properties of the resultingmaterial.

SUMMARY OF THE INVENTION

With the present invention, it has been possible to reduce or eliminatethe drawbacks of the known methods and devise a process for productionof macrostructures of microporous materials with controlled size, shapeand porosity.

One objective of the present invention is to reduce or eliminate thedrawbacks in the known methods for production of microporousmacrostructures with a new process that permits production of thesestructures without addition of binders and with a uniform finalcomposition. Another objective of the present invention is to provide aprocess, according to which the final shape, size and size distributionof the structure can be controlled with high precision by selecting thestarting material. Still another objective of the present invention isto provide a process according to which both the micropore structure ofthe material and a secondary system of larger pores can be controlled byselecting the starting material and synthesis conditions. A furtherobjective of the present invention is to provide a process forproduction of macrostructures of microporous material with goodmechanical and thermal stability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 represents a schematic description of the different stages inproduction of spherical particles or thin films of microporous materialaccording to the invention.

FIG. 2 represents adsorption-desorption isotherms measured for sphericalparticles of amorphous silica of Examples 1 and 2.

FIG. 3 and FIG. 4 show SEM micrographs, at two different magnifications,of spherical particles of the molecular sieve silicalite-1 of Example 3.

FIG. 5 is an X-ray diffraction pattern for spherical particles of themolecular sieve silicalite-1 of Example 3.

DETAILED DESCRIPTION OF THE INVENTION

The present invention concerns a process for the production ofmacrostructures of microporous material, characterized by the fact thatseeds formed in or introduced by ion exchange or adsorption to a porousorganic ion exchanger with the desired size, shape and porosity, aremade to grow and form a continuous structure by further deposition ofinorganic material from a synthesis solution under hydrothermalconditions, and that the organic ion exchanger is then eliminated suchas by chemical destruction or dissolution and, in so doing, leavesbehind an inorganic microporous structure with the size and shape of theemployed organic ion exchanger. A schematic description of the methodaccording to the invention is shown in FIG. 1.

Microporous material refers to a material in which most of the specificsurface area is found in pores with a diameter below 20 Å. A crystallinemicroporous material, usually called molecular sieves or zeolites, is ofspecial interest for the invention. Materials like silicalite-1, ZSM-5,zeolites A, Y, mordenite, Beta, L, ZSM-2, X and hydroxysodalite are ofspecial interest. Different types of amorphous silicates are also ofinterest.

Macrostructures refer to structures with a size that exceeds 0.01 mm inone dimension, preferably 0.1 mm and, in most cases, 1.0 mm. Examples ofmacrostructures are spherical particles, cylindrical extrudates,pellets, fibers, thin films applied to different forms of substrates andother composites, in which the microporous material is combined withother types of material.

Organic ionic exchanger refers to a polymer-based porous material with afixed surface charge and with high ion exchange capacity for anions orcations. A large number of different types of organic ion exchangers arecommercially available including organic ion exchanges sold under thetradenames Dowex and Amberlite. This covers a broad spectrum ofdifferent cation and anion exchangers with varying ion exchangecapacity, porosity, pore size and particle size. Ion exchangers with anapparent anion exchange capacity, typically greater than about 1 meg/gmof dry anion exchanger, are of special interest to the presentinvention. Ion exchangers of the strongly basic type, containingquaternary ammonium groups, have been found to be particularly suitedfor use in the present invention. Commercially available ion exchangersare generally in the form of spherical particles with a relativelynarrow particle size distribution. Organic ion exchangers with a sizeand shape other than spherical, for example, fibers or flakes, however,can be produced according to known techniques. It is also known thatfilms of organic ion exchangers can be deposited on different forms ofsubstrates.

The term “seeds” refers to silicate species, metal silicate species oraluminosilicate species present in the synthesis mixtures or formed inan early stage of synthesis, characterized by the fact that by treatmentin a solution with appropriate concentration and under suitableconditions, they can be made to grow and form a continuous structure inthe pore system of the ion exchanger. The term “seeds” also includesmicrocrystals, i.e., crystals of molecular sieves with a size below 200nm, and whose crystal structure can be identified by X-ray diffraction.Production of microcrystals of molecular sieves suitable as seeds forproduction of microporous macrostructures according to the invention isdescribed in WO 94/05597 which is hereby incorporated by reference.

In a second phase in production of microporous macrostructures accordingto the invention, the seeds formed on or bonded to the surface in theorganic ion exchanger are made to grow by hydrothermal treatment in anappropriate synthesis solution. Through this growth a continuousthree-dimensional network of microporous material is formed in the porestructure of the employed ion exchange structure. After this stage, theproduct is therefore a composite material, consisting of two continuousthree-dimensional networks, one organic, consisting of the polymerstructure of the ion exchanger, and one inorganic, consisting of theintroduced inorganic microporous material. Introduction of seeds can becarried out physically in a separate stage, with a subsequent growthstage under hydrothermal conditions in a synthesis solution. However, itis also possible and often advantageous not to separate these stages butinstead to directly introduce the ion exchanger material into asynthesis solution and expose this to hydrothermal conditions, duringwhich seeds are formed in or ion-exchanged from the synthesis solutionto the ion exchanger, to then grow into a continuous structure.

Molecular sieves of the zeolite or crystalline microporous metalsilicate type are generally produced by hydrothermal treatment of asilicate solution with well-defined composition. This composition andthe synthesis parameters, like temperature, time and pressure, dictatewhich type of product is obtained and the size and shape in the crystalsthat are formed. This applies both in syntheses, in which the finalproduct is deposited as crystals in the porous structure of an ionexchanger, and in conventional synthesis, when the final crystal size ismost often much larger. The type of material deposited in the poresystem of the ion exchanger is therefore dependent on the composition ofthe synthesis mixture and the conditions during synthesis. Duringcrystallization of macrostructures of a given molecular sieve accordingto the present invention, it has been found suitable to use synthesismixtures, which, in the absence of ion exchanger material, result incolloidal suspensions of the molecular sieve in question. In some cases,the ion exchanger material has also been found to influence the resultof synthesis. For example, when certain ion exchanger materials areused, an amorphous macrostructure of microporous silica with very largespecific surface area can be produced by means of a synthesis solutionand under conditions which, in the absence of an ion exchanger produce acrystalline molecular sieve. A parameter of great interest in thisconnection has been found to be the ratio between amount of ionexchanger and amount of synthesis solution. Under otherwise identicalconditions and during the use of the same synthesis solution, a lowratio between the amount of ion exchanger and amount of synthesissolution yields a well crystallized product; whereas an intermediateratio yields a mixture of crystalline and amorphous microcrystallinematerial, and a high ratio leads to an entirely amorphous microporousmaterial. Hydrothermal treatment refers to treatment in aqueous solutionor aqueous suspension at a temperature exceeding 50° C., preferablyexceeding 80° C. and, in most cases, exceeding 95° C.

The composite of ion exchanger and microporous inorganic materialobtained after this process can be of interest by itself in certaincommercial applications. However, for most potential areas ofapplication it is advantageous to eliminate the organic ion exchangerstructure. This can occur in a last stage of the process according tothe invention, which leaves behind only a microporous material with asecondary pore system with a porosity and pore size caused by thestructure of the employed organic ion exchanger. Elimination of theorganic material that makes up the ion exchanger preferably occurs bycalcining at a temperature exceeding 400° C. in the presence of air, inwhich this material is burned to mostly carbon dioxide and water. As analternative, the organic material can be eliminated by selectivedissolution with a solvent that dissolves the ion exchanger, but not theinorganic material, or with selective decomposition of the inorganicmaterial by means of a chemical reaction other than a combustionreaction.

The resulting material according to the invention is a replica in sizeand shape of the organic ion exchanger used as starting material. Thismeans that the possibilities for controlling the size, shape andmeso/macroporosity in the inorganic microporous material are largelydetermined by the possibilities of structural manipulation of theproperties of the ion exchanger. The secondary pore structure thatdevelops during removal of the organic ion exchanger material, however,can be further manipulated by continued deposition after removal of thismaterial. By growth of the inorganic structure after this stage, thesecondary pore structure can be more or less sealed and, in the extremecase, leave behind a homogeneous microporous material (without porosityin the meso/macropore range). This could be of interest, for example, inthe production of thin films of microporous structures, for use inapplications, like membranes for catalyst or separation purposes, or inchemical sensors. It is also possible, according to a known technique,to coat the surface of the macrostructures of a given type ofmicroporous material produced according to the invention with a thinfilm of another type of material, something that could be of interest ina catalytic context or during use of macrostructures for controlleddosage of drugs or pesticides.

The process according to the present invention was evaluated by means ofinvestigation of materials produced according to the process with ascanning electron microscope (SEM), X-ray diffractometry (XRD),spectroscopy and by measurements of the specific surface area and poresize distribution with krypton or nitrogen adsorption.

Scanning electron microscope studies were conducted on samples coatedwith gold (by a sputtering technique). A scanning electron microscope ofthe Philips XL 30 type with a Lanthanum hexa-Boride emission source wasused in these studies.

X-ray diffraction studies were conducted with a Siemens D-5000 powderdiffractometer.

Nitrogen adsorption measurements to determine specific surface area andparticle size distribution were carried out with an ASAP 2010 fromMicrometrics Instruments, Inc.

Elemental analysis concerning carbon, nitrogen and hydrogen was carriedout on certain samples by means of an analytical instrument from LECOCorporation (LECO CHN-600). The particle size and particle sizedistribution for the colloidal suspensions of discrete microcrystals ofmolecular sieves used as starting material according to the process wereinvestigated by dynamic light scattering (ZetaPlus, BrookhavenInstruments).

The following examples illustrate the invention are not but intended tolimit the invention.

EXAMPLE 1

This example describes production of spherical particles of microporousamorphous silica with very high specific surface area.

A synthesis solution with the composition (on a molar basis): 9 TPAOH/25SiO₂/480 H₂O/100 EtOH (TPAOH=tetrapropylammonium hydroxide,EtOH=ethanol) was produced by mixing 20.0 grams tetraethoxysilane (>98%,Merck), 34.56 grams tetrapropylammonium hydroxide (1.0M solution, Sigma)and 5.65 grams distilled water. The mixture was allowed to hydrolyze ina polyethylene flask on a shaking table for 12 hours at roomtemperature. 1.0 grams of a strongly basic anion exchanger of the Dowex1×2-100 type was added to 10 grams of this synthesis solution. The anionexchanger was present as spherical particles in the particle size range50-100 mesh (dry) and had an ion exchange capacity specified by themanufacturer of 3.5 mEq/g. The mixture of ion exchanger and synthesissolution was treated in a polyethylene reactor equipped with a refluxcondenser in an oil bath at 100° C. for 48 hours. After this time, theion exchanger particles were separated from the solution by filtrationand treated in a 0.1M ammonia solution in an ultrasound bath for 15minutes, whereupon they were separated again by means of filtration. Theparticles were finally washed three times by suspension in distilledwater, followed by separation by filtration, and then dried in a heatingcabinet at 60° C. for 12 hours. The particles were finally calcined at600° C. in air for 4 hours, after heating to this temperature at a rateof 10° C./min.

The resulting material consisted of very hard, solid, white sphericalparticles with a size distribution identical to that in the employed ionexchanger. Elemental analysis showed that the particles were almostentirely free of carbon, hydrogen and nitrogen, which clearly shows thatthe ion exchanger material had been completely eliminated in thecalcining stage. X-ray diffractometry also showed that the material wascompletely amorphous. The particles were further analyzed by nitrogenadsorption measurements at the boiling point of nitrogen to determinethe specific surface area, the adsorption isotherm and pore sizedistribution. The specific surface area was calculated from theadsorption data according to the BET equation as 1220 m²/g. The recordedisotherm is shown in FIG. 2 and was of type I, which is typical ofmicroporous materials. Calculation of the pore size distribution by theBJH method (desorption isotherm) showed that a very small fraction(about 20 m²/g) of the total specific surface area of the material wasfound in pores in the mesopore range (diameter >20 Å). The average porediameter was calculated at 9.5 Å by the Horvath-Kawazoes method.

EXAMPLE 2

This example describes production of spherical particles of amorphousaluminum silicate with high specific surface area in pores in both themicro- and mesopore range.

25 grams of a synthesis solution with the molar composition: 2.4Na₂O/1.0 TEACl/0.4 Al₂O₃/10 SiO₂/460 H₂O (TEACl=tetraethylammoniumchloride) were added to 2.0 grams of a strongly basic ion exchanger ofthe type Dowex MSA-1 (particle size 20-50 mesh and [dry] ion exchangecapacity of 4 mEq/g) in a polyethylene reactor. The synthesis mixturewas prepared by first dissolving 0.75 grams sodium aluminate (50.6 wt %Al₂O₃, 36 wt % Na₂O) in 35 grams of a 1M NaOH solution at 100° C. Thissolution was then added to a mixture of 40 grams distilled water, 1.66grams TEACl (Merck) and 15 grams silica sol (Bindzil 40/130, EkaChemicals AB, solids content 41.36 wt %, 0.256 wt % Na₂O) duringagitation for 2 hours. The mixture of ion exchanger and synthesissolution was treated in a polyethylene reactor equipped with a refluxcondenser in an oil bath at 100° C. for 48 hours. After this time, theion exchanger particles were separated from the solution by filtrationand treated in a 0.1M ammonia solution in an ultrasound bath for 15minutes, whereupon they were separated again by filtration. Theparticles were finally washed three times by suspension in distilledwater, followed by separation by filtration, and then dried in a heatingcabinet at 60° C. for hours. The particles were finally calcined at 600°C. in air for 4 hours, after heating to this temperature at a rate of10° C./min.

Visual inspection and analysis with a scanning electron microscopeshowed that the resulting material consisted of very hard, solid, whitespherical particles with size distribution identical to that in theemployed ion exchanger. Elemental analysis showed that the particleswere almost entirely free of carbon, hydrogen and nitrogen, whichclearly shows that the ion exchanger material had been fully eliminatedin the calcining stage. X-ray diffractometry also showed that thematerial was completely amorphous. The particles were further analyzedby nitrogen adsorption measurements at the boiling point of nitrogen todetermine the specific surface area, adsorption isotherms and pore sizedistribution. The specific surface area was calculated from theadsorption data according to the BET equation as 594 m²/g. The recordedisotherm is shown in Example 2 and was of type IV. Calculation of thepore size distribution by the BJH method (desorption isotherm) showedthat a relatively large percentage of the total (cumulative) pore volume(about 65%) was found in pores in the mesopore range (radius >20 Å).

EXAMPLE 3

This example describes production of spherical particles of molecularsieve silicalite-1 with the process according to the invention.

14.3 grams of a synthesis solution with the molar composition: 9TPAOH/25 SiO₂/480 H₂O/100 EtOH were added to 1.0 grams of macroporousstrongly basic ion exchanger of the Dowex MSA-1 type (particle size20-50 mesh [dry]; ion exchange capacity: 4 mEq/g). The synthesis mixturewas prepared as described in Example 1. The mixture of ion exchanger andsynthesis solution was treated in a polyethylene reactor equipped with areflux condenser in an oil bath at 100° C. for 48 hours. After thistime, the ion exchanger particles were separated from the solution andthe material was crystallized in the bulk phase by filtration andtreated in a 0.1M ammonia solution in an ultrasound bath for 15 minutes,whereupon they were separated again by filtration. The particles werefinally washed three times by suspension in distilled water, followed byseparation by filtration, and then dried in a heating cabinet at 60° C.for 12 hours. The particles were finally calcined at 600° C. in air for10 hours, after heating to this temperature at a rate of 1° C./min.

Visual inspection and scanning electron microscopy revealed that theresulting material consisted of very hard, solid (homogeneous), whitespherical particles with a size distribution identical to that in theemployed ion exchanger. Elemental analysis showed that the particleswere almost entirely free of carbon, hydrogen and nitrogen, whichclearly shows that the ion exchanger material was fully eliminated inthe calcining stage. FIGS. 3 and 4 are two SEM photographs of theproduct taken at two different magnifications. FIG. 3 taken at the lowermagnification shows the spherical character of the particles, whereasFIG. 4 taken at high magnification shows the presence of small primaryparticles (primary crystals) with a size of about 100 nm. X-raydiffractometry revealed that the material is crystalline and consists ofsilicalite-1, but that it also contains a percentage of amorphousmaterial. An X-ray diffraction pattern for this sample is shown in FIG.5. Analysis with nitrogen adsorption gave a specific surface area of 438m²/g and showed that most of the pore volume was found in microporeswith an average pore diameter of 6 Å, calculated according to theHorvath-Kawazoes method.

EXAMPLE 4

This example describes production of spherical particles of molecularsieve zeolite ZSM-5 with the process according to the invention.

15 grams of a synthesis solution with the molar composition: 0.58 Na₂O/9TPAOH/0.5 Al₂O₃/25 SiO₂/405 H₂O were added to 1.0 grams of a macroporousstrongly basic anion exchanger of the Dowex MSA-1 type (particle size20-50 mesh [dry]; ion exchange capacity: 4 mEq/g). The synthesis mixturewas prepared by first dissolving 0.408 grams of aluminum isopropoxide(Sigma) in 10 grams of 1.0M tetrapropylammonium hydroxide (Sigma).Another solution was prepared by dissolving 6.0 grams freeze-driedsilica sol (Bindzil 30/220, 31 wt % SiO₂, 0.5 wt % Na₂O Eka Chemicals,AB) in 26 grams 1.0M TPAOH at 100° C. The two solutions were mixedduring agitation for 30 minutes. The mixture of ion exchanger andsynthesis solution was treated in a polyethylene reactor equipped with areflux condenser in an oil bath at 100° C. for 20 days. After this time,the ion exchanger particles were separated from the solution and thematerial was crystallized in the bulk phase by filtration and treated ina 0.1M ammonia solution in an ultrasound bath for 15 minutes, whereuponthey were separated again by filtration. The particles were finallywashed three times by suspension in distilled water, followed byseparation by filtration, and then dried in a heating cabinet at 50° C.for 12 hours. The particles were finally calcined at 600° C. in air for10 hours, after heating to this temperature at a rate of 1° C./min.

Visual inspection and analysis with a scanning electron microscopeshowed that the product largely consisted of white, solid particles witha size and shape identical to that of the employed ion exchanger. Arelatively large fraction of the product, however, was shown to consistof particles with roughly the same size as the employed ion exchanger,but with a more irregular shape. SEM analysis at high magnificationshowed that the particles consisted of intergrown crystals with amorphology typical of MFI structures and with a size of about 1 μm.X-ray diffractometry showed that the particles consisted of zeoliteZSM-5, but also a relatively large fraction of amorphous material. Thespecific surface area was measured by nitrogen adsorption at 612 m²/g.

EXAMPLE 5

This example describes production of spherical particles of molecularsieve zeolite A with the process according to the invention.

18.0 grams of a synthesis solution with the molar composition: 0.22Na₂O/5.0 SiO₂/Al₂O₃/8 TMA₂O/400 H₂O were added to 1.0 grams of astrongly basic anion exchanger of the Dowex MSA-1 type. The synthesismixture was prepared by first dissolving 1.25 grams of aluminumisopropoxide (Sigma) and 9.0 grams tetramethylammonium hydroxidepentahydrate (Sigma) in 0.90 grams of 1.0M solution of NaOH and 3.0grams water during agitation for 2 hours. This solution was added, inturn, to a mixture of 3.0 grams silica sol (Bindzil 30/220, see Example4) and 12 grams of distilled water, whereupon the resulting solution wasagitated for 3 hours. The mixture of ion exchanger and synthesissolution was treated in a polyethylene reactor equipped with a refluxcondenser in an oil bath at 100° C. for 10 hours. After this time, theion exchanger particles were separated from the solution and thematerial was crystallized in the bulk phase by filtration and treated ina 0.1M ammonia solution in an ultrasound bath for 15 minutes, whereuponthey were separated again by filtration. The particles were finallywashed three times by suspension in distilled water, followed byseparation by filtration, and then dried in a heating cabinet at 60° C.for 12 hours. The particles were finally calcined at 600° C. in air for10 hours, after heating to this temperature at a rate of 1° C./min.

Visual inspection and analysis by scanning electron microscopy showedthat the product largely consisted of light brown, solid particles witha size and shape identical to that of the employed ion exchanger. Asmaller fraction of the product consisted of fragmented particles. SEMat high magnification showed that the particles are homogeneous andconstructed from intergrown primary particles with a size up to about300 nm. X-ray diffractometry showed that the resulting materialcontained zeolite A and a certain amount of amorphous material. Nitrogenadsorption measurements gave a specific surface area (according to theBET equation) of 306 m²/g and indicated the presence of both micro- andmesoporosity.

EXAMPLE 6

This example describes production of spherical particles of molecularsieve zeolite Beta using the process according to the invention.

15 grams of a synthesis solution with the molar composition: 0.35 Na₂O/9TEAOH/0.5 Al₂O₃/25 SiO₂/295 H₂O were added to 1.0 grams of a stronglybasic anion exchanger of the Dowex MSA-1 type. The synthesis mixture wasprepared by dissolving 0.81 grams aluminum isopropoxide (Sigma) in 6.0grams tetraethylammonium hydroxide (TEAOH, 20% solution) at 100° C. Thissolution was added to a solution of 6.0 grams freeze-dried silica sol(Bindzil 30/220, see Example 4) dissolved in 20 grams of TEAOH (20%solution) and the resulting solution was agitated for 30 minutes. Themixture of ion exchanger and synthesis solution was treated in apolyethylene reactor equipped with a reflux condenser in an oil bath at100° C. for 8 days. After this time, the ion exchanger particles wereseparated from the solution and the material was crystallized in thebulk phase by filtration and treated in a 0.1M ammonia solution in anultrasound bath for 15 minutes, whereupon the particles were separatedagain by filtration. The particles were finally washed three times bysuspension in distilled water, followed by separation by filtration, andthen dried in a heating cabinet at 60° C. for 12 hours. The particleswere finally calcined at 600° C. in air for 10 hours, after heating tothis temperature at a rate of 1° C./min.

Visual inspection, as well as analysis with a scanning electronmicroscope, showed that the product largely consisted of hard, white,solid particles with a size and shape identical to that of the employedion exchanger. SEM analysis at high magnification shows that thematerial is constructed of intergrown primary particles with a size ofabout 80 nm. X-ray diffractometry showed that the particles containedzeolite Beta as the only crystalline phase. The specific surface areacalculated with the BET equation, based on nitrogen adsorption data, was580 m²/g.

EXAMPLE 7

This example describes how a film of molecular sieve silicalite-1 can bebuilt up on the surface of a macrostructure of silicalite-1 producedaccording to Example 3.

10.0 grams of synthesis solution with the composition and preparationaccording to Example 3 were added to 0.20 grams of calcined productproduced according to Example 3. This mixture was treated at 100° C. ina polyethylene reactor equipped with a reflux condenser for 48 hours.After this time, the particles were separated from the solution and thematerial was crystallized in the bulk phase by filtration and treated ina 0.1M ammonia solution in an ultrasound bath for 15 minutes, whereuponthey were separated again by filtration. The particles were finallywashed three times by suspension in distilled water, followed byseparation by filtration, and then dried in a heating cabinet at 60° C.for 12 hours. Part of the material was calcined at 600° C. for 10 hours,after heating to this temperature at a rate of 1° C./min. X-raydiffraction measurements on the calcined sample revealed that the samplecontained silicalite-1 as the only crystalline phase. Scanning electronmicroscopy detected an outer layer of silicalite-1 on the surface of theparticles, a layer that synthesis had built up from about 300/-nm largeprimary particles. The specific surface area was determined for theuncalcined sample as 92 m²/g, whereas the corresponding value measuredfor the calcined sample was 543 m²/g. The difference in the surfacebefore and after calcining indicates that the outer shell ofsilicalite-1 effectively encloses the open pore system in the originalparticles.

1. A composite material comprising a porous organic ion-exchanger and acrystalline continuous three-dimensional network of inorganic materialcomprising a microporous material having pores with a diameter less than20 Å formed inside the pore structure of said porous organicion-exchanger.
 2. The composite material recited in claim 1, whereinsaid porous organic ion-exchanger is a porous organic anionicion-exchanger.
 3. The composite material recited in claim 2, whereinsaid porous anionic ion-exchanger has an ion-exchange capacity greaterthan about 1 meg./gm of dry porous anionic ion-exchanger.
 4. Thecomposite material recited in claim 2, wherein said porous organicanionic ion-exchanger is a basic anion-exchange resin containingquartenary ammonium groups.
 5. The composite material recited in claim1, wherein said microporous material is a crystalline molecular sievecomprising a zeolite or a metallo-silicate substantially free ofaluminum.
 6. The composite material recited in claim 5, wherein saidcrystalline molecular sieve is selected from the group consisting ofsilicalite 1, hydroxysodalite, zeolite A, zeolite beta, zeolite X,zeolite Y, ZSM-2, ZSM-5, mordenite, and zeolite L.
 7. The compositematerial recited in claim 5, wherein said crystalline molecular sieve isa ZSM-5 or silicalite
 1. 8. The composite material recited in claim 5,wherein said crystalline molecular sieve is a ZSM-5.
 9. A compositematerial comprising a crystalline continuous three-dimensional networkof inorganic material comprising a microporous material formed insidethe pore structure of a porous organic ion-exchanger.
 10. The compositematerial recited in claim 9, wherein said porous organic ion-exchangeris a porous organic anionic ion-exchanger.
 11. The composite materialrecited in claim 10, wherein said porous anionic ion-exchanger has anion-exchange capacity greater than about 1 meg./gm of dry porous anionicion-exchanger.
 12. The composite material recited in claim 10, whereinsaid porous organic anionic ion-exchanger is a basic anion-exchangeresin containing quartenary ammonium groups.
 13. The composite materialrecited in claim 9, wherein said microporous material is a crystallinemolecular sieve comprising a zeolite or a metallo-silicate substantiallyfree of aluminum.
 14. The composite material recited in claim 13,wherein said crystalline molecular sieve is selected from the groupconsisting of silicalite 1, hydroxysodalite, zeolite A, zeolite beta,zeolite X, zeolite Y, ZSM-2, ZSM-5, mordenite, and zeolite L.
 15. Thecomposite material recited in claim 13, wherein said crystallinemolecular sieve is a ZSM-5 or silicalite
 1. 16. The composite materialrecited in claim 13, wherein said crystalline molecular sieve is aZSM-5.